System for suspending processing by a first electronic device on a data line to allow a second electronic device to use the data line, with subsequent resumption of the processing of the first electronic device

ABSTRACT

To provide a method for controlling a transmission system with quick response in which plural electronic devices are connected to one host apparatus through a common data line. The method for controlling the transmission system of the present invention comprises: a step of transmitting a command signal for releasing the data line and suspending the processing through a command signal line to the electronic device occupying the data line in the state where one of the plural electronic devices is executing the processing that occupies the data line so as to make the electronic device release the data line and suspend the processing and to perform data transmission between the host apparatus and the other one of the electronic devices; and a step of resuming the suspended processing after the data transmission between the host apparatus and the other electronic device.

TECHNICAL FIELD

The present invention relates to a host apparatus, electronic devices,and a method for controlling a transmission system having a hostapparatus and electronic devices.

BACKGROUND ART

There is a transmission system in which a host apparatus (masterapparatus) is connected to plural electronic devices (slave devices)through a common data line and data is transmitted between the hostapparatus and the plural electronic devices.

In such transmission system, generally, the host apparatus permits aspecific electronic device to occupy a data line and then datatransmission between the host apparatus and the electronic device (datatransmission from the host apparatus to the electronic device or datatransmission from the electronic device to the host apparatus) isexecuted. When the data transmission is completed, the host apparatuspermits another electronic device to occupy the data line and then datatransmission between the host apparatus and the electronic device isexecuted.

However, in the conventional transmission system in which pluralelectronic devices are connected to one host apparatus through thecommon data line (for example, data bus), while one electronic device isoccupying the data line, data transmission between other electronicdevice and the host apparatus cannot be executed. The other electronicdevice is obliged to wait until the initial electronic device hasfinished processing (including data transmission) and then execute datatransmission.

To solve the above-mentioned conventional problem, the present inventionintends to provide a transmission system with quick response, whereineven while one electronic device is occupying a data line, datatransmission between the other electronic device and the host apparatuscan be performed as necessary and plural electronic devices areconnected to one host apparatus through a common data line, a method forcontrolling the transmission system, and a host apparatus and electronicdevices constituting the transmission system.

DISCLOSURE OF THE INVENTION

To solve the above-mentioned problem, the present invention has thefollowing configuration.

A host apparatus from one aspect of the present invention comprises aninput/output part having a command signal line for transmitting acommand signal from the host apparatus to an electronic device and aresponse signal from the above-mentioned electronic device to the hostapparatus in response to the above-mentioned command signal, and a dataline, at least a part of which is commonly used by plural electronicdevices and connected to the plural electronic devices, fortransmitting, at least, data in connection with the command signal fromthe host apparatus to the above-mentioned electronic device; and acontrol part having a saving register for bus release, and theabove-mentioned control part

in the state where one of the above-mentioned electronic devices isexecuting the processing that occupies the above-mentioned data line,when data transmission between the host apparatus and the other one ofthe above-mentioned electronic devices is intended to be executed,transmits a command signal for releasing the above-mentioned data lineand suspending the above-mentioned processing to the electronic devicethat occupies the above-mentioned data line through the above-mentionedcommand signal line;

stores an identifier of the electronic device that occupies theabove-mentioned data line and the information on the current stage ofthe above-mentioned processing in the above-mentioned saving registerfor bus release;

after completion of data transmission between the host apparatus and theabove-mentioned other electronic device, reads out the identifier of theelectronic device that had occupied the above-mentioned data line andthe information on the current stage of the above-mentioned processingfrom the above-mentioned saving register for bus release; and

transmits a command signal for returning to the above-mentionedsuspended processing to the electronic device that had occupied theabove-mentioned data line through the above-mentioned command signalline.

A host apparatus from another aspect of the present invention comprisesan input/output part having a command signal line for transmitting acommand signal from the host apparatus to an electronic device and aresponse signal from the above-mentioned electronic device to the hostapparatus in response to the above-mentioned command signal, and a dataline, at least a part of which is commonly used by plural electronicdevices and connected to the plural electronic devices, fortransmitting, at least, data in connection with the command signal fromthe host apparatus to the above-mentioned electronic device; and acontrol part having a saving register for bus release, and

the above-mentioned control part

in the state where one of the above-mentioned electronic devices isexecuting the processing that occupies the above-mentioned data line,when data transmission between the host apparatus and the other one ofthe above-mentioned electronic devices is intended to be executed,transmits a command signal for releasing the above-mentioned data lineand suspending the above-mentioned processing to the above-mentionedplural electronic devices connected to the above-mentioned data linethrough the above-mentioned command signal line;

stores the information that the above-mentioned data line has beenreleased and the information on the current stage of the above-mentionedprocessing in the above-mentioned saving register for bus release;

after completion of data transmission between the host apparatus and theabove-mentioned other electronic device, reads out the information thatthe above-mentioned data line has been released and the information onthe current stage of the above-mentioned processing from theabove-mentioned saving register for bus release; and

transmits a command signal for returning to the above-mentionedsuspended processing to the above-mentioned plural electronic devicesconnected to the above-mentioned data line through the above-mentionedcommand signal line.

In the above-mentioned host apparatus from another aspect of the presentinvention,

the above-mentioned input/output part further has an interrupt signalline for transmitting an interrupt signal from the above-mentionedelectronic device to the host apparatus;

the above-mentioned control part further has an interrupt prioritydetermination part;

in the case where the host apparatus receives the interrupt signal forrequesting data transmission from the other one of the above-mentionedelectronic devices through the above-mentioned interrupt signal line inthe state where one of the above-mentioned electronic devices isexecuting the processing that occupies the above-mentioned data line;and

the above-mentioned interrupt priority determination part determinesthat the above-mentioned data transmission has a higher priority thanthe processing that occupies the above-mentioned data line,

there is a case where data transmission between the host apparatus andthe above-mentioned other electronic device is intended to be executedin the state where one of the above-mentioned electronic devices isexecuting the processing that occupies the above-mentioned data line.

The above-mentioned electronic device from another aspect of the presentinvention comprises an input/output part having a command signal linefor transmitting a command signal from the host apparatus to anelectronic device and a response signal from the above-mentionedelectronic device to the host apparatus in response to theabove-mentioned command signal, and a data line, at least a part ofwhich is commonly used by plural electronic devices and connected to theplural electronic devices, for transmitting, at least, data inconnection with the command signal from the host apparatus to theabove-mentioned electronic device; and a control part having a savingregister for bus release, and

the above-mentioned control part

in the state where the electronic device is executing the processingthat occupies the above-mentioned data line, when receiving a commandsignal for releasing the above-mentioned data line and suspending theabove-mentioned processing from the above-mentioned host apparatus,stores the information on the current stage of the above-mentionedprocessing in the above-mentioned saving register for bus release,suspends the above-mentioned processing and transmits a response signalfor notifying that the above-mentioned processing has been suspended andthe above-mentioned data line has been released to the above-mentionedhost apparatus through the above-mentioned command signal line;

when receiving a command signal for returning to the above-mentionedsuspended processing from the above-mentioned host apparatus through theabove-mentioned command signal line, transmits a response signalincluding the information that return of the above-mentioned processingis possible and the information as to whether the data line need to bereoccupied or not to the above-mentioned host apparatus through theabove-mentioned command signal line, reads out the information on thecurrent signal of the above-mentioned processing from theabove-mentioned saving register for bus release, resumes theabove-mentioned processing from the above-mentioned stage, and if thereis need to reoccupy the above-mentioned data line, transmits datathrough the above-mentioned data line.

A method for controlling a transmission system from another aspect ofthe present invention comprises a host apparatus, plural electronicdevices, a command signal line for transmitting a command signal fromthe host apparatus to an electronic device and a response signal fromthe above-mentioned electronic device to the host apparatus in responseto the above-mentioned command signal, and a data line, at least a partof which is commonly used by plural electronic devices and connected tothe plural electronic devices, for transmitting, at least, data inconnection with the command signal from the host apparatus to theabove-mentioned electronic device; and

the above-mentioned method comprises the steps of:

in the state where one of the above-mentioned plural electronic devicesis executing the processing that occupies the above-mentioned data line,transmitting an command signal for releasing the above-mentioned dataline and suspending the above-mentioned processing from the hostapparatus to the above-mentioned electronic device that occupies theabove-mentioned data line through the above-mentioned command signalline in order to execute data transmission between the above-mentionedhost apparatus and the other one of the above-mentioned electronicdevices;

transmitting a response signal for notifying that the above-mentionedprocessing has been suspended and the above-mentioned data line has beenreleased from the electronic device that occupies the above-mentioneddata line to the above-mentioned host apparatus through theabove-mentioned command signal line;

after completion of data transmission between the above-mentioned hostapparatus and the above-mentioned other electronic device, transmittingan command signal for returning to the above-mentioned suspendedprocessing from the host apparatus to the electronic device that hadoccupied the above-mentioned data line through the above-mentionedcommand signal line;

transmitting a response signal including the information that return ofthe above-mentioned processing is possible and the information as towhether the data line need to be reoccupied or not from the electronicdevice that had occupied the above-mentioned data line to theabove-mentioned host apparatus through the above-mentioned commandsignal line; and

if the electronic device that had occupied the above-mentioned data lineneed to reoccupy the above-mentioned data line, transmitting datathrough the above-mentioned data line and resuming the above-mentionedprocessing.

A method for controlling a transmission system from another aspect ofthe present invention comprises a host apparatus, plural electronicdevices, a command signal line for transmitting a command signal fromthe host apparatus to an electronic device and a response signal fromthe above-mentioned electronic device to the host apparatus in responseto the above-mentioned command signal, and a data line, at least a partof which is commonly used by plural electronic devices and connected tothe plural electronic devices, for transmitting, at least, data inconnection with the command signal from the host apparatus to theabove-mentioned electronic device; and

the above-mentioned method comprises the steps of:

in the state where one of the above-mentioned plural electronic devicesis executing the processing that occupies the above-mentioned data line,transmitting an command signal for releasing the above-mentioned dataline and suspending the above-mentioned processing from the hostapparatus to the above-mentioned plural electronic devices connected tothe above-mentioned data line through the above-mentioned command signalline in order to execute data transmission between the above-mentionedhost apparatus and the other one of the above-mentioned electronicdevices;

transmitting a response signal for notifying that the above-mentionedprocessing has been suspended and the above-mentioned data line has beenreleased from the electronic device that occupies the above-mentioneddata line to the above-mentioned host apparatus through theabove-mentioned command signal line;

after completion of data transmission between the above-mentioned hostapparatus and the above-mentioned other electronic device, transmittingan command signal for returning to the above-mentioned suspendedprocessing from the host apparatus to the above-mentioned pluralelectronic devices connected to the above-mentioned data line throughthe above-mentioned command signal line;

transmitting a response signal including the information that return ofthe above-mentioned processing is possible and the information as towhether the data line need to be reoccupied or not from the electronicdevice that had occupied the above-mentioned data line to theabove-mentioned host apparatus through the above-mentioned commandsignal line; and

if the electronic device that had occupied the above-mentioned data lineneed to reoccupy the above-mentioned data line; transmitting datathrough the above-mentioned data line and resuming the above-mentionedprocessing.

In a method for controlling the above-mentioned transmission system fromanother aspect of the present invention, the above-mentionedtransmission system further comprises an interrupt signal line fortransmitting an interrupt signal from the above-mentioned electronicdevice to the host apparatus, and

the above-mentioned method comprises the steps of:

in the state where one of the above-mentioned electronic devices isexecuting the processing that occupies the above-mentioned data line,the above-mentioned host apparatus receiving an interrupt signal forrequesting data transmission from the other one of the above-mentionedelectronic devices through the above-mentioned interrupt signal line;and

determining that the above-mentioned data transmission has a higherpriority than the processing that occupies the above-mentioned dataline; and

based on the result of the above-mentioned determination, there is acase where data transmission between the above-mentioned host apparatusand the above-mentioned other electronic device is intended to beexecuted in the state wherein one of the above-mentioned electronicdevices is executing the processing that occupies the above-mentioneddata line.

In a method for controlling the above-mentioned transmission system fromanother aspect of the present invention, the above-mentioned pluralelectronic devices have an identifier for distinguishing from each otherand at least either of the above-mentioned command signal or theabove-mentioned response signal has the above-mentioned identifier.

A host apparatus from another aspect of the present invention comprisesan input/output part having a communication line for transmitting acommand signal from the host apparatus to an electronic device and aresponse signal from the above-mentioned electronic device to the hostapparatus in response to the above-mentioned command signal; and acontrol part having a saving register, and

the above-mentioned control part

in the state of performing communication processing with one of theabove-mentioned electronic devices, when the host apparatus intends tocommunicate with the other one of the above-mentioned electronicdevices, transmits a command signal for suspending the above-mentionedcommunication processing to the above-mentioned electronic devicethrough the above-mentioned communication line;

stores an identifier of the above-mentioned electronic device and theinformation on the current stage of the above-mentioned communicationprocessing in the above-mentioned saving register;

after completion of communication between the host apparatus and theabove-mentioned other electronic device, reads out the identifier of theabove-mentioned electronic device and the information on the currentstage of the above-mentioned communication processing from theabove-mentioned saving register; and

transmits a command signal for returning to the above-mentionedsuspended communication processing to the above-mentioned electronicdevice through the above-mentioned communication line.

The present invention has an effect of realizing the method forcontrolling the transmission system wherein, even while one electronicdevice is occupying the data line, data transmission between the otherelectronic device and the host apparatus can be executed and pluralelectronic devices are connected to one host apparatus through thecommon data line, and a host apparatus and electronic devicesconstituting the transmission system.

The present invention has an effect that, even while the host apparatusis communicating one electronic device, the host apparatus can suspendthe communication and communicate with the other electronic device, ifnecessary. The host apparatus can resume communicate with the initialelectronic device efficiently. This achieves an advantageous effect thata transmission system with quick response in which plural electronicdevices are connected to one host apparatus, a method for controllingthe system, a host apparatus and electronic devices constituting thetransmission system can be realized.

The novel features of the invention are set forth with particularity inthe appended claims. The invention as to both structure and content, andother objects and features thereof will best be understood from thedetailed description when considered in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of a transmissionsystem in accordance with a first embodiment of the present invention.

FIG. 2 is a time chart of the transmission system in accordance with thefirst embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of a transmissionsystem in accordance with a second embodiment of the present invention.

FIG. 4 is a time chart of the transmission system in accordance with thesecond embodiment of the present invention.

FIG. 5 is a block diagram showing the configuration of a transmissionsystem in accordance with a third embodiment of the present invention.

FIG. 6 is a time chart of the transmission system in accordance with thethird embodiment of the present invention.

FIG. 7 is a block diagram showing the configuration of a transmissionsystem in accordance with a fourth embodiment of the present invention.

FIG. 8 is a block diagram showing the configuration of a transmissionsystem in accordance with a fifth embodiment of the present invention.

FIG. 9 is a time chart of the transmission system in accordance with thefifth embodiment of the present invention.

Part or All of the drawings are drawn schematically for diagrammaticrepresentation and it should be considered that they do not necessarilyreflect relative size and position of components shown therein.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments embodying best mode for carrying out the present inventionwill be described along with drawings.

First Embodiment

FIG. 1 is a block diagram showing the configuration of a transmissionsystem in accordance with a first embodiment of the present invention.

FIG. 1 shows a host apparatus 101, n number of electronic devices (wheren is an integer of 2 or more) 102, 103, and 104, command signal lines105, 106 and 107, and a data line 108. In FIG. 1, the electronic device1 (102), the electronic device 2 (103) and the electronic device n (104)stand for n number of electronic devices.

The host apparatus 101 has a control part 111 and an input/output part112. The control part 111 has a saving register for bus release 121. Thehost apparatus 101 may be any electronic device and in the firstembodiment, a portable electronic device (for example, portableinformation terminal). The host apparatus 101 has a unique identifier.The unique identifier is, for example, a unique combination of 8-digitalphanumeric characters.

The electronic device 1 has a control part 113 and an input/output part114. The control part 113 has a saving register for bus release 122.

The electronic devices 2 to n (103 to 104) have the same or differentfunction that the electronic device 1 has, and each of them has thecontrol part 113 and the input/output part 114. In FIG. 1, descriptionof block configuration within the electronic devices 2 to n (103 to 104)is omitted.

The electronic devices 1 to n (102 to 104) each have an arbitraryfunction such as memory, wireless communicating part, wire communicatingpart, camera or so on. The electronic devices 1 to n (102 to 104) eachhave a unique identifier.

The electronic devices 1 to n (102 to 104) may be stored in theirrespective housings separately or included in a housing altogether.

In the first embodiment, the electronic devices 1 to n (102 to 104) areincluded in an IC card having multiple functions. In the firstembodiment, the IC card having multiple functions is a SD (SecureDigital) card. The electronic devices 1 to n (102 to 104) are functionalblocks for carrying out each of multiple functions.

The host apparatus 101 and the electronic devices 1 to n (102 to 104)constitute an information transmission system. In the transmissionsystem, the host apparatus 101 serves as a master and the electronicdevices 1 to n (102 to 104) serve as slaves.

The input/output part 112 of the host apparatus 101 is connected to theinput/output parts *114 of the electronic devices 1 to n (102 to 104) bythe command signal lines 105 to 107 and a data line 108. The commandsignal lines 105 to 107 each connect the input/output part 112 of thehost apparatus 101 to the input/output parts 114 of the electronicdevices 1 to n (102 to 104) independently. Therefore, the host apparatus101 can issue a command to all of the electronic devices 1 to n (102 to104) at any given timing.

The command signal lines 105 to 107 transmit a command signal from thehost apparatus 101 to the electronic devices 1 to n (102 to 104) and aresponse signal from the electronic devices 1 to n (102 to 104) to thehost apparatus 101 in response to the command signal.

In the transmission system of the first embodiment, the electronicdevices 1 to n (102 to 104) are connected to the host apparatus 101through the common data line 108. The data line 108 transmits data fromthe host apparatus 101 to the electronic devices 1 to n (102 to 104) anddata from the electronic devices 1 to n (102 to 104) to the hostapparatus 101.

The command signal lines and the data line may be either a single lineor plural lines (bus). In the first embodiment, each of the commandsignal lines 105 to 107 is a single line and the data line 108 consistsof four bus lines.

Signal transmission through the command signal lines and the data linemay be either synchronous transmission or asynchronous transmission. Inthe first embodiment, synchronous transmission is adopted. Theinput/output part 112 of host apparatus 101 sends a clock signal fortransmitting the command signal, response signal and data to theinput/output parts 114 of the electronic devices 1 to n (102 to 104)through a clock signal line (not shown).

FIG. 2 is a schematic diagram for illustrating transmission of thecommand signal, response signal and data between the host apparatus 101and the electronic devices 1 to n (102 to 104) in the transmissionsystem in accordance with the first embodiment of the present invention.FIG. 2 shows the following case in detail: especially when oneelectronic device is occupying the data line, data transmission betweenthe other electronic device and the host apparatus is executed.

The transmission system of the first embodiment uses the protocol thatthe host apparatus 101 transmits a command signal to one of theelectronic devices and then the electronic device that received thecommand signal returns a response signal to the host apparatus andfurther, if necessary, data is transmitted from the host apparatus tothe electronic device or from the electronic device to the hostapparatus.

Referring to FIG. 1 and FIG. 2, operations of the transmission system inaccordance with the first embodiment of the present invention will bedescribed.

In FIG. 2, firstly, the control part 111 of the host apparatus 101 sendsa command signal 201 (including an identifier of the host apparatus 101as a source and an identifier of the electronic device 1 as adestination) for requesting data transmission to the electronic device 1(102) through the command signal line 105. In response to the commandsignal 201, the control part 113 of the electronic device 1 (102)transmits a response signal 202 (including an identifier of theelectronic device 1as a source and an identifier of the host apparatus101 as a destination) including information that transmission ispossible (for example, an ACK signal) to the host apparatus 101 throughthe command signal line 105 and further transmits data 211 to the hostapparatus 101 through the data line 108. As the data line 108 isoccupied by the electronic device 1 (102), the other electronic devices2 to n (103 to 104) cannot use the data line 108.

In the first embodiment, as each of the command signal lines 105 to 107connects the host apparatus 101 to one of the electronic devices, sourceand destination of the command signal and the response signal areobvious. Therefore, the command signal and the response signal need notinclude identifiers of source and destination.

However, assuming that the control part 111 of the host apparatus 101has to transmit data to the electronic device 2 (103) while transmittingdata 211 from the electronic device 1 (102) to the host apparatus 101.In the transmission system of the first embodiment, the control part 111of the host apparatus 101 transmits a command signal 203 (including anidentifier of the host apparatus 101 as a source and an identifier ofthe electronic device 1 as a destination) for releasing the data line(data bus) 108 and suspending the processing that the electronic device1 is executing (processing including data transmission) to theelectronic device 1 (102) through the command signal line 105.

The control part 111 stores the information that the data line 108 hasbeen released, the information on the current stage of the processingbeing currently executed (processing including data reception) and theidentifier of the electronic device 1 (102) in a saving register for busrelease 121.

In the first embodiment, the saving register for bus release 121 has abus release flag. The bus release flag is generally set to 0, andchanged to 1 when the control part 111 sends a command signal forreleasing the data line (data bus) 108 during data transmission. Afterresumption of the suspended data transmission, the bus release flag isreturned to 0 by the control part 111. In the first embodiment, theinformation that the data line 108 has been released means that the busrelease flag of the saving register for bus release 121 is changed to 1.

The control part 113 of the electronic device 1 (102) receives thecommand signal 203 from the host apparatus 101, stores the informationthat data transmission has been suspended and the information on thecurrent stage of the processing being currently executed (processingincluding data transmission) in a saving register for bus release 122,suspends the processing and releases the data line 108.

In the first embodiment, the saving register for bus release 122 has abus release flag. The bus release flag is generally set to 0, andchanged to 1 when the control part 111 of the electronic device 1 (102)receives a command signal for releasing the data line (data bus) 108during data transmission. After the electronic device 1 (102) receives acommand signal for resuming data transmission from the host apparatus101 and resumes data transmission, the bus release flag is returned to 0by the control part 113 of the electronic device 1 (102). In the firstembodiment, the information that data transmission has been suspendedmeans that the bus release flag of the saving register for bus release122 is changed to 1.

“Information on the current stage of the processing being currentlyexecuted” may be any information by which data transmission can besuspended on the way and then resumed from the suspended point. Forexample, assuming that the electronic device 1 (102) receives a commandto release the data line (data bus) (command signal from the hostapparatus 101.) while transmitting data at the addresses 200 to 800 in abuilt-in RAM to the host apparatus 101 through the data line 108, andsuspends data transmission at the point when data at the address 425 hasbeen transmitted. The control part 111 of the host apparatus 101 and thecontrol part 113 of the electronic device 1 (102) store the informationthat the electronic device 1 was executing the task of transmitting dataat the addresses 200 to 800 in the built-in RAM and the last address 425(or a first address 426 at the time of resumption) in a specific storagearea, and further store an address of the specific storage area in thesaving resisters for bus release 121, 122. Accordingly, when datatransmission is resumed, the control part 111 of the host apparatus 101and the control part 113 of the electronic device 1 (102) need only readout the address of the specific storage area from the saving resistersfor bus release 121, 122, read out the task content and the last address425 (or the first address 426 at the time of resumption) from thespecific storage area and transmit data at the addresses 426 to 800.

In response to a bus release command (command signal 203), the controlpart 113 of the electronic device 1 (102) transmits a response signal204 (including an identifier of the electronic device 1 (102) as asource and an identifier of the host apparatus 101 as a destination) forsuspending the processing and notifying that the data line 108 has beenreleased to the above-mentioned host apparatus 101 through the commandsignal line 105.

Based on the response signal 204, the control part 111 of the hostapparatus 101 finds that the data line 108 has been released. Then, thecontrol part 111 sends a command signal 205 (including an identifier ofthe host apparatus 101 as a source and an identifier of the electronicdevice 2 as a destination) for requesting to receive data transmittedfrom the host apparatus 101 to the electronic device 2 (103) through thecommand signal line 106. In response to the command signal 205, thecontrol part 113 of the electronic device 2 (103) transmits a responsesignal 206 (including an identifier of the electronic device 2 as asource and an identifier of the host apparatus 101 as a destination)including information that reception is possible (for example, an ACKsignal) to the host apparatus 101 through the command signal line 106.Next, data 212 is transmitted from the host apparatus 101 to theelectronic device 2 (103) through the data line 108.

When data transmission between the host apparatus 101 and the electronicdevice 2 (103) is finished, the control part 111 of the host apparatus101 reads out the information that the data line 108 has been released,the information on the current stage of the processing being currentlyexecuted (processing including data reception) and the identifier of theelectronic device 1 (102) from the saving register for bus release 121.Based on the information, the control part 111 finds that the electronicdevice 1 (102) has suspended the processing so as to release the bus.The control part 111 of the host apparatus 101 transmits a commandsignal (bus return command) 207 (including an identifier of the hostapparatus 101 as a source and an identifier of the electronic device 1as a destination) for returning to the processing suspended by theelectronic device 1 (processing that occupies the data line) to theelectronic device 1 (102) through the above-mentioned command signalline.

The control part 113 of the electronic device 1 (102) receives thecommand signal (bus return command) 207 and transmits a response signal208 (including an identifier of the electronic device 2 as a source andan identifier of the host apparatus 101 as a destination) including theinformation that return of processing is possible and the information asto whether the data line need to be reoccupied or not (In FIG. 2, thedata line need to be reoccupied.) to the host apparatus 101 through thecommand signal line 105.

The control part 113 of the electronic device 1 (102) reads out theinformation that data transmission has been suspended on the way and theinformation on the current stage of the processing being currentlyexecuted (processing including data transmission) from a saving registerfor bus release 122. Similarly, the control part 111 of the hostapparatus 101 reads out the information on the current stage of theprocessing being currently executed (processing including datareception) from a saving register for bus release 121.

Based on the information on the current stage of the processing beingcurrently executed (processing including data transmission), the controlpart 111 and the control part 113 resume the suspended data transmissionfrom the suspended point. In FIG. 2, the control part 113 transmits data213 to the host apparatus 101 through the data line 108.

The control part 111 of the host apparatus 101 sets the bus release flagof the saving register for bus release 121 to be 0. Similarly, thecontrol part 113 of the electronic device 1 (102) sets the bus releaseflag of the saving register for bus release 122 to be 0.

In the transmission system in accordance with the first embodiment ofthe present invention in which plural electronic devices are connectedto one host apparatus through the common data line, even while oneelectronic device is occupying the data line, a release period 221 ofthe data line (FIG. 2) can be provided by transmitting the command torelease the data line and the command to return data transmission fromthe host apparatus to the electronic device that occupies the data line.Whereby, data transmission between the host apparatus and the otherelectronic device can be performed during the release period 221 of thedata line. After completion of data transmission between the hostapparatus and the other electronic device, it becomes possible to resumedata transmission between the host apparatus and the electronic devicethat had occupied the data line.

In the transmission system in accordance with the first embodiment ofthe present invention, a command signal line for transmitting a commandsignal from the host apparatus and a response signal to the commandsignal from the electronic devices is provided with each electronicdevice independently.

Second Embodiment

FIG. 3 is a block diagram showing the configuration of a transmissionsystem in accordance with a second embodiment of the present invention.

FIG. 3 shows a host apparatus 301, n number of electronic devices (wheren is an integer of 2 or more) 302, 303, and 304, a command signal line305 and a data line 306. In FIG. 3, the electronic device 1 (302), theelectronic device 2 (303) and the electronic device n (304) stand for nnumber of electronic devices.

The host apparatus 301 has a control part 311 and an input/output part312. The control part 311 has a saving register for bus release 321. Thehost apparatus 301 may be any electronic device and in the firstembodiment, a portable electronic device (for example, a cellularphone). The host apparatus 301 has a unique identifier. The uniqueidentifier is, for example, a unique combination of 8-digit alphanumericcharacters.

The electronic device 1 has a control part 313 and an input/output part314. The control part 313 has a saving register for bus release 322.

The electronic devices 2 to n (303 to 304) have the same or differentfunction that the electronic device 1 (302) has, and each of them hasthe control part 313 and the input/output part 314. In FIG. 3,description of block configuration within the electronic devices 2 to n(303 to 304) is omitted.

The electronic devices 1 to n (302 to 304) have an arbitrary functionsuch as memory, wireless communicating part, wire communicating part,camera or so on. The electronic devices 1 to n (302 to 304) each have aunique identifier.

The electronic devices 1 to n (302 to 304) may be stored in theirrespective housings separately or included in a housing altogether.

In the second embodiment, the electronic devices 1 to n (302 to 304) areincluded in an IC card having multiple functions. In the secondembodiment, the IC card having multiple functions is a SD card. Theelectronic devices 1 to n (302 to 304) are functional blocks forcarrying out each of multiple functions.

The host apparatus 301 and the electronic devices 1 to n (302 to 304)constitute an information transmission system. In the transmissionsystem, the host apparatus 301 serves as a master and the electronicdevices 1 to n (302 to 304) serve as slaves.

The input/output 312 of the host apparatus 301 is connected to theinput/output parts 314 of the electronic devices 1 to n (302 to 304) bythe command signal line 305 and the data line 306. The command signalline 305 is a common line that connects the input/output 312 of the hostapparatus 301 to the input/output parts 314 of the electronic devices 1to n (302 to 304). Accordingly, the host apparatus 301 can issue acommand to all of the electronic devices at a time. Moreover, it canissue a command to a specific electronic device by using the identifierfor identifying the electronic device.

The command signal line 305 transmits a, command signal from the hostapparatus 301 to the electronic devices 1 to n (302 to 304) and aresponse signal from the electronic devices 1 to n (302 to 304) to thehost apparatus 301 in response to the command signal.

In the transmission system of the second embodiment, the electronicdevices 1 to n (302 to 304) are connected to the host apparatus 101through the common data line 306. The data line 306 transmits data fromthe host apparatus 301 to the electronic devices 1 to n (302 to 304) anddata from the electronic devices 1 to n (302 to 304) to the hostapparatus 301.

The command signal line and the data line may be either a single line orplural lines (bus). In the second embodiment, the command signal line305 is a single line and the data line 306 consists of four bus lines.

Signal transmission through the command signal line and the data linemay be either synchronous transmission or asynchronous transmission. Inthe second embodiment, synchronous transmission is adopted. Theinput/output part 312 of host apparatus 301 sends a clock signal fortransmitting the command signal, response signal and data to theinput/output parts 314 of the electronic devices 1 to n (302 to 304)through a clock signal line (not shown).

FIG. 4 is a diagram for illustrating the command signal, response signaland data between the host apparatus 301 and the electronic devices 1 ton (302 to 304) in the transmission system in accordance with the secondembodiment of the present invention. FIG. 4 shows the following case indetail: especially when one electronic device is occupying the dataline, data transmission between the other electronic device and the hostapparatus is performed.

The transmission system of the second embodiment uses the protocol thatthe host apparatus 301 transmits a command signal to one of theelectronic devices and then the electronic device that received thecommand signal returns a response signal to the host apparatus andfurther, if necessary, data is transmitted from the host apparatus tothe electronic device or from the electronic device to the hostapparatus.

Referring to FIG. 3 and FIG. 4, operations of the transmission system inaccordance with the second embodiment of the present invention will bedescribed.

In FIG. 4, firstly, the control part 311 of the host apparatus 301 sendsa command signal 401 (including an identifier of the host apparatus 301as a source and an identifier of the electronic device 1 as adestination) for requesting the electronic device 1 (302) to receivedata transmitted from the host apparatus through the command signal line305. In response to the command signal 401, the control part 313 of theelectronic device 1 (302) transmits a response signal 402 (including anidentifier of the electronic device 1as a source and an identifier ofthe host apparatus 301 as a destination) including information thatreception is possible (for example, an ACK signal) to the host apparatus301 through the command signal line 305. The host apparatus 301transmits data 411 to the electronic device 1 (302) through the dataline 306. As the data line 306 is occupied by the electronic device 1(302), the other electronic devices 2 to n (303 to 304) cannot use thedata line 306.

However, assuming that the control part 311 of the host apparatus 301has to receive data from the electronic device 2 (303) whiletransmitting data 411 from the host apparatus 301 to the electronicdevice 1 (302). In the transmission system of the second embodiment, thecontrol part 311 of the host apparatus 301 transmits a command signal403 (including an identifier of the host apparatus 301 as a source andnot including an identifier of a destination) for releasing the dataline (data bus) 306 and suspending the processing that the electronicdevice 1 is executing (processing including data reception) to all ofthe electronic devices 1 to n (302 to 304) through the command signalline 305.

The control part 311 stores the information that the data line 306 hasbeen released, and the information on the current stage of theprocessing being currently executed (processing including datatransmission) in a saving register for bus release 321.

The control part 313 of the electronic device 1 (302) that occupies thedata line currently receives the command signal 403 from the hostapparatus 301, stores the information that data reception has beensuspended and the information on the current stage of the processingbeing currently executed (processing including data reception) in asaving register for bus release 322, suspends the processing andreleases the data line 306. As the other electronic devices 2 to n (303to 304) do not use the data line currently, they ignore the commandsignal 403.

In response to a bus release command (command signal 403), the controlpart 313 of the electronic device 1 (302) transmits a response signal404 (including an identifier of the electronic device 1 (302) as asource and an identifier of the host apparatus 301 as a destination) forsuspending the processing and notifying that the data line 306 has beenreleased to the above-mentioned host apparatus 301 through the commandsignal line 305.

Based on the response signal 404, the control part 311 of the hostapparatus 301 finds that the data line 306 has been released. Then, thecontrol part 311 sends a command signal 405 (including an identifier ofthe host apparatus 301 as a source and an identifier of the electronicdevice 2 as a destination) for requesting data transmission to theelectronic device 2 (303) through the command signal line 305. Inresponse to the command signal 405, the control part 313 of theelectronic device 2 (303) transmits a response signal 406 (including anidentifier of the electronic device 2 as a source and an identifier ofthe host apparatus 301 as a destination) including information that datatransmission is possible (for example, an ACK signal) to the hostapparatus 301 through the command signal line 305. Next, data 412 istransmitted from the host apparatus 301 to the electronic device 2 (303)through the data line 306.

When data transmission between the host apparatus 301 and the electronicdevice 2 (303) is finished, the control part 311 of the host apparatus301 reads out the information that the data line 306 has been releasedand the information on the current stage of the processing beingcurrently executed (processing including data transmission) from thesaving register for bus release 321. Based on the information, thecontrol part 311 finds that the processing has been suspended so as torelease the bus. The control part 311 of the host apparatus 301transmits a command signal (bus return command) 407 (including anidentifier of the host apparatus 301 as a source and an identifier ofthe electronic device 1, and not including an identifier of adestination) for returning to the suspended processing (processing thatoccupies the data line) to all of the electronic devices 1 to n (302 to304) through the above-mentioned command signal line.

Based on the information reads out from the saving register for busrelease 322 that data reception has been suspended on the way, thecontrol part 313 of the electronic device 1 (302) finds that the acommand signal 407 from the host apparatus 301 is a command signal theelectronic addressed to the electronic device 1 (302).

As there is no information that data reception has been suspended on theway in the saving register for bus release 322, the other electronicdevices 2 to n (303 to 304) ignore the command signal 407.

The control part 313 of the electronic device 1 (302) receives thecommand signal (bus return command) 407 and transmits a response signal408 (including an identifier of the electronic device 2 as a source andan identifier of the host apparatus 301 as a destination) including theinformation that return of processing is possible and the information asto whether the data line need to be reoccupied or not (In FIG. 4, thedata line need to be reoccupied.) to the host apparatus 301 through thecommand signal line 305.

The control part 311 of the host apparatus 301 reads out the informationon the current stage of the processing being currently executed(processing including data transmission) from a saving register for busrelease, 321. Similarly, the control part 313 of the electronic device 1(302) reads out the information on the current stage of the processingbeing currently executed (processing including data transmission) from asaving register for bus release 322.

Based on the information on the current stage of the processing beingcurrently executed (processing including data transmission), the controlpart 311 of the host apparatus 301 resumes the suspended datatransmission from the suspended point. In FIG. 4, the control part 311transmits data 413 to the electronic device 1 (302) through the dataline 306.

In the transmission system of the second embodiment, the bus releasecommand and the bus return command include no identifier of thedestination. In other embodiments, the bus release command and the busreturn command include identifiers of the source and the destination.

In the transmission system in accordance with the second embodiment ofthe present invention in which plural electronic devices are connectedto one host apparatus through the common data line, even while oneelectronic device is occupying the data line, a release period 421 ofthe data line (FIG. 4) can be provided by transmitting the command torelease the data line and the command to return data transmission fromthe host apparatus to the electronic device that occupies the data line.Whereby, data transmission between the host apparatus and the otherelectronic device can be executed during the release period 421 of thedata line. After completion of data transmission between the hostapparatus and the other electronic device, it becomes possible to resumedata transmission between the host apparatus and the electronic devicethat had occupied the data line.

Third Embodiment

FIG. 5 is a block diagram of a transmission system in accordance with athird embodiment of the present invention.

FIG. 5 shows a host apparatus 501, n number of electronic devices (wheren is an integer of 2 or more) 502, 503, and 504, command signal lines505, 506 and 507, and a data line 108. In FIG. 5, the electronic device1 (502), the electronic device 2 (503) and the electronic device n (504)stand for n number of electronic devices.

The host apparatus 501 has a control part 512 and an input/output part513. The control part 512 has a saving register for bus release 521 andan interrupt priority determination part 522. The host apparatus 501 maybe any electronic device and in the third embodiment, a portableelectronic device (for example, portable an information terminal). Thehost apparatus 501 has a unique identifier. The unique identifier is,for example, a unique combination of 8-digit alphanumeric characters.

The electronic device 1 has a control part 514 and an input/output part515. The control part 514 has a saving register for bus release 523.

The electronic devices 2 to n (503 to 504) have the same or differentfunction that the electronic device 1 has, and each of them has thecontrol part 514 and the input/output part 515. In FIG. 5, descriptionof block configuration within the electronic devices 2 to n (503 to 504)is omitted.

The electronic devices 1 to n (502 to 504) have an arbitrary function.The electronic devices 1 to n (502 to 504) each have a uniqueidentifier.

The electronic devices 1 to n (502 to 504) may be stored in theirrespective housings separately or included in a housing altogether.

In the third embodiment, the electronic devices 1 to n (502 to 504) areincluded in an IC card having multiple functions. In the thirdembodiment, the IC card having multiple functions is a SD card. Theelectronic devices 1 to n (502 to 504) are functional blocks forcarrying out each of multiple functions.

The host apparatus 501 and the electronic devices 1 to n (502 to 504)constitute an information transmission system. In the transmissionsystem, the host apparatus 501 serves as a master and the electronicdevices 1 to n (502 to 504) serve as slaves.

The input/output part 513 of the host apparatus 501 is connected to theinput/output parts 515 of the electronic devices 1 to n (502 to 504) bythe command signal lines 505 to 507, a data line 508 and interruptsignal lines 509 to 511. The command signal lines 505 to 507 eachconnect the input/output part 513 of the host apparatus 501 to theinput/output parts 515 of the electronic devices 1 to n (502 to 504)independently. Therefore, the host apparatus 501 can issue a command toall of the electronic devices 1 to n (502 to 504) at any given timing.

The command signal lines 505 to 507 transmit a command signal from thehost apparatus 501 to the electronic devices 1 to n (502 to 504) and aresponse signal from the electronic devices 1 to n (502 to 504) to thehost apparatus 501 in response to the command signal.

In the transmission system of the third embodiment, the electronicdevices 1 to n (502 to 504) are connected to the host apparatus 501through the common data line 508. The data line 508 transmits data fromthe host apparatus 501 to the electronic devices 1 to n (502 to 504) anddata from the electronic devices 1 to n (502 to 504) to the hostapparatus 501.

The command signal lines and the data line may be either a single lineor plural lines (bus). In the third embodiment, each of the commandsignal lines 505 to 507 is a single line and the data line 508 consistsof two bus lines.

Signal transmission through the command signal lines and the data linemay be either synchronous transmission or asynchronous transmission. Inthe third embodiment, synchronous transmission is adopted. Theinput/output part 513 of host apparatus 501 sends a clock signal fortransmitting the command signal, response signal and data to theinput/output part 515 of the electronic devices 1 to n (502 to 504)through a clock signal line (not shown).

The interrupt signal lines 509 to 511 each connects the input/outputparts 515 of the electronic devices 1 to n (502 to 504) to theinput/output part 513 of the host apparatus 501 independently.Therefore, each of the electronic devices 1 to n (502 to 504) can issuean interrupt signal to the host apparatus 501 at any give timing.

The interrupt signal lines 509 to 511 transmits an interrupt signal fromeach of the electronic devices 1 to n (502 to 504) to the host apparatus501.

FIG. 6 is a diagram for illustrating the command signal, response signaland data between the host apparatus 501 and the electronic devices 1 ton (502 to 504) in the transmission system in accordance with the thirdembodiment of the present invention. FIG. 6 shows the following case indetail: especially when one electronic device is occupying the dataline, data transmission between the other electronic device and the hostapparatus is executed.

The transmission system of the third embodiment uses the protocol thatthe host apparatus 501 transmits a command signal to one of theelectronic devices and then the electronic device that received thecommand signal returns a response signal to the host apparatus andfurther, if necessary, data is transmitted from the host apparatus tothe electronic device or from the electronic device to the hostapparatus.

The transmission system of the third embodiment is similar to thetransmission system of the first embodiment. In the transmission systemof the first embodiment, in the case where the host apparatus 101intends to transmit or receive data to or from the electronic deviceother than the electronic device that occupies the data line currently,the electronic device that occupies the data line currently is made torelease the data line and data transmission between the host apparatusand the electronic device other than the electronic device that occupiesthe data line currently is executed.

In addition to the above-mentioned case, in the transmission system ofthe third embodiment, in the case where the electronic device (slave)intends to transmit or receive data to or from the host apparatus whilethe other electronic device is occupying the data line, the electronicdevice that occupies the data line currently is made to release the dataline by sending an interrupt signal to the host apparatus, so that datatransmission between the electronic device and the host apparatus can beexecuted.

Referring to FIG. 5 and FIG. 6, operations of the transmission system inaccordance with the third embodiment of the present invention will bedescribed. Description of the same operations as those in the firstembodiment is omitted.

In FIG. 6, firstly, the control part 512 of the host apparatus 501 sendsa command signal 601 for requesting data transmission to the electronicdevice 1 (502) through the command signal line 505. In response to thecommand signal 601, the electronic device 1 (502) transmits a responsesignal 602 including information that transmission is possible (forexample, an ACK signal) to the host apparatus 501 through the commandsignal line 505, and further transmits data 611 to the host apparatus501 through the data line 508. As the data line 508 is occupied by theelectronic device 1 (502), the other electronic devices 2 to n (503 to504) cannot use the data line 508.

However, assuming that the electronic device 2 (503) has to receive datafrom the host apparatus 501 while transmitting data 611 from theelectronic device 1 (502) to the host apparatus 501. The control part515 of the electronic device 2 (503) transmits an interrupt signal 614to the host apparatus 501 through the interrupt signal line 510.

When receiving the interrupt signal 614, the interrupt prioritydetermination part 522 of the control part 512 of the host apparatus 101determines which of data transmission that being performed currently ordata transmission requested from the electronic device 2 (503) should begiven priority. In FIG. 6, the interrupt priority determination part 522determines that data transmission requested from the electronic device 2(503) should be given priority.

The host apparatus 501 transmits a command signal 603 for releasing thedata line (data bus) 508 and suspending the processing that theelectronic device 1 is executing (processing including datatransmission) to the electronic device 1 (502) through the commandsignal line 505.

The electronic device 1 (502) receives the command signal 603, suspendsthe processing (including data transmission) and releases the data line508.

In response to the bus release command (command signal 603), theelectronic device 1 (502) transmits a response signal 604 for suspendingthe processing (including data transmission) and notifying that the dataline 508 has been released to the above-mentioned host apparatus 501through the command signal line 505.

Based on the response signal 604, the host apparatus 501 finds that thedata line 508 has been released. Then, the host apparatus 501 sends acommand signal 605 for notifying that data is transmitted from the hostapparatus 501 to the electronic device 2 (503) in response to theinterrupt signal 614 through the command signal line 506. In response tothe command signal 605, the control part 514 of the electronic device 2(503) transmits a response signal 606 including the information thatdata reception is possible (for example, an ACK signal) to the hostapparatus 501 through the command signal line 506. Next, data 612 istransmitted from the host apparatus 501 to the electronic device 2 (503)through the data line 508.

When data transmission between the host apparatus 501 and the electronicdevice 2 (503) is finished, the host apparatus 501 transmits a commandsignal (bus return command) 607 for returning to the suspendedprocessing (processing that occupies the data line) to the electronicdevice 1 (502) through the command signal line 505.

The electronic device 1 (502) receives the command signal (bus returncommand) 607 and transmits a response signal 608 including theinformation that return of processing is possible and the information asto whether the data line need to be reoccupied or not (In FIG. 6, thedata line need to be reoccupied.) to the host apparatus 501 through thecommand signal line 505.

The electronic device 1 (502) resumes the suspended data transmissionfrom the suspended point. In FIG. 6, the electronic device 1 (502)transmits data 613 to the host apparatus 501 through the data line 508.

In the transmission system in accordance with the third embodiment ofthe present invention in which plural electronic devices are connectedto one host apparatus through the common data line, even while oneelectronic device is occupying the data line, a release period 621 ofthe data line (FIG. 6) can be provided by transmitting the command torelease the data line and the command to return data transmission fromthe host apparatus to the electronic device that occupies the data line.Whereby, data transmission between the host apparatus and the otherelectronic device can be performed during the release period 621 of thedata line. After completion of data transmission between the hostapparatus and the other electronic device, it becomes possible to resumedata transmission between the host apparatus and the electronic devicethat had occupied the data line.

A command signal line that sends a command from the host apparatus and aresponse of the electronic device in response to the command is providedseparately for each electronic device and the command to suspend andresume data transmission are transmitted through the command signalline, thereby that the transmission system in which the other electronicdevice with higher priority is capable of executing data transmissioneven during processing that occupies the data line can be realized.

Fourth Embodiment

FIG. 7 is a block diagram showing the configuration of a transmissionsystem in accordance with a fourth embodiment of the present invention.The transmission system of the fourth embodiment is similar to thetransmission system of the third embodiment (FIG. 5).

In the transmission system of the third embodiment, the host apparatus501 is connected to n number of electronic devices 502 to 504 (n is anintegers of 2 or more) by n number of command signal lines 505 to 507independently, and interrupt signal lines 508 to 511 from n number ofelectronic devices 502 to 504 to the host apparatus 501 are n number oflines separated from each other.

In the transmission system of the fourth embodiment, the host apparatus701 is connected to n number of (n is an integers of 2 or more)electronic devices 702 to 704 by a common command signal line 705, andthe host apparatus 701 and n number of electronic devices 702 to 704each have a unique identifier and transmits a command signal and aresponse signal with unique identifiers indicating source anddestination through a command signal line 705.

In the transmission system of the fourth embodiment, the host apparatus701 is connected to n number of (n is an integers of 2 or more)electronic devices 702 to 704 by a common interrupt signal line 709.When inputting an interrupt signal, the host apparatus 701 makes theelectronic device that occupies the bus release the data line once(transmits a bus release command) and then transmits a command signalfor inquiring content of the interrupt request to all of the electronicdevices 702 to 704. The electronic device that sent the interrupt signalreturns the response signal for notifying content of the interruptrequest (an identifier of the electronic device is added) to the hostapparatus 701 through the command signal line 705.

Based on the response signal, the host apparatus 701 judges whichelectronic device makes what interrupt request, and an interruptpriority determination part 722 determines whether the interruptprocessing should be given priority or not. In the case where processingof the electronic device that occupies the data line currently is givenpriority, bus return command is sent to the electronic device to resumedata transmission. In the case where processing of the electronic devicethat sends the interrupt request is given priority, the processing isexecuted, and after completion of the processing, bus return command issent to the electronic device that had occupied the data line to resumedata transmission.

The transmission system of the fourth embodiment can achieve the sameeffect as the transmission system of the third embodiment.

Fifth Embodiment

FIG. 8 is a block diagram of a transmission system in accordance with afifth embodiment of the present invention.

FIG. 8 shows a host apparatus 801, n number of electronic devices (wheren is an integer of 2 or more) 802 to 804, command signal lines 805 to807 and data lines 808 to 810. In FIG. 8, the electronic device 1 (802),the electronic device 2 (803) and the electronic device n (804) standfor n number of electronic devices.

The host apparatus 801 has a control part 811 and an input/output part812. The control part 811 has a saving register for bus release 821. Thehost apparatus 801 may be any electronic device and in the fifthembodiment, a portable electronic device (for example, portable acellular phone). The host apparatus 801 has a unique identifier. Theunique identifier is, for example, a unique combination of 8-digitalphanumeric characters.

The electronic device 1 has a control part 813 and an input/output part814. The control part 813 has a saving register 822.

The electronic devices 2 to n (803 to 804) have the same or differentfunction that the electronic device 1 (802) has, and each of them hasthe control part 813 and the input/output part 814. In FIG. 8,description of block configuration within the electronic devices 2 to n(803 to 804) is omitted.

The electronic devices 1 to n (802 to 804) have an arbitrary functionsuch as memory, wireless communicating part, wire communicating part,camera or so on. The electronic devices 1 to n (802 to 804) each have aunique identifier.

The electronic devices 1 to n (802 to 804) may be stored in theirrespective housings separately or included in a housing altogether.

In the fifth embodiment, the electronic devices 1 to n (802 to 804) areincluded in an IC card having multiple functions. In the fifthembodiment, the IC card having multiple functions is a SD card. Theelectronic devices 1 to n (802 to 804) are functional blocks forcarrying out each of multiple functions.

The host apparatus 801 and the electronic devices 1 to n (802 to 804)constitute an information transmission system. In the transmissionsystem, the host apparatus 801 serves as a master and the electronicdevices 1 to n (802 to 804) serve as slaves.

The input/output part 812 of the host apparatus 801 is connected to theinput/output parts 814 of the electronic devices 1 to n (802 to 804) bythe command signal line 805 to 807 and the data lines 808 to 810.

The command signal lines 805 to 807 transmit a command signal from thehost apparatus 801 to the electronic devices 1 to n (802 to 804) and aresponse signal from the electronic devices 1 to n (802 to 804) to thehost apparatus 801 in response to the command signal.

The data lines 808 to 810 transmit data from the host apparatus 801 tothe electronic devices 1 to n (802 to 804) and data from the electronicdevices 1 to n (802 to 804) to the host apparatus 801.

In the transmission system of the fifth embodiment, as a dedicatedcommand signal line and data line are provided with each electronicdevice, communication of two electronic devices does not compete witheach other on the command signal line or the data line. However, it isassumed that the following case occurs.

While communicating with one electronic device (for example, theelectronic device 1), the host apparatus has to communicate with theother electronic device (for example, the electronic device 2). Thenewly required communication has a higher priority than thecommunication that being executed currently. As simultaneouscommunication with two electronic devices exceeds an upper limit ofthroughput capacity of the host apparatus (having a microcomputer), thehost apparatus cannot communicate with two electronic devicessimultaneously. In such case, the host apparatus 801 of the fifthembodiment suspends the current communication and executes the newlyrequired communication with higher priority. After completion of thecommunication, previous communication is resumed from the suspendedpoint. FIG. 9 is a diagram for illustrating the command signal, responsesignal and data between the host apparatus 801 and the electronicdevices 1 to n (802 to 804) in the above-mentioned case.

The transmission system of the fifth embodiment uses the protocol thatthe host apparatus 801 transmits a command signal to one of theelectronic devices and then the electronic device that received thecommand signal returns a response signal to the host apparatus andfurther, if necessary, data is transmitted from the host apparatus tothe electronic device or from the electronic device to the hostapparatus.

Referring to FIG. 8 and FIG. 9, operations of the transmission system inaccordance with the second embodiment of the present invention will bedescribed.

In FIG. 9, firstly, the control part 811 of the host apparatus 801 sendsa command signal 901 to the electronic device 1 (802). In response tothe command signal 901, the control part 813 of the electronic device 1(802) transmits a response signal 902 to the host apparatus 801. Thehost apparatus 801 transmits data 911 to the electronic device 1 (802)through the data line 808.

However, assuming that the control part 811 of the host apparatus 801has to receive data from the electronic device 2 (803) whiletransmitting data 911 from the host apparatus 801 to the electronicdevice 1 (802). Priority of the communication is high. The control part811 of the host apparatus 801 transmits a command signal 903 forsuspending the processing that the electronic device 1 is executing(processing including data reception) to the electronic device 1 (802).

The control part 811 stores the information on the current stage of theprocessing being currently executed (processing including datatransmission) in a saving register for bus release 821.

The control part 813 of the electronic device 1 (802) that is performingcommunication currently receives the command signal 903 from the hostapparatus 801, stores the information that data reception has beensuspended and the information on the current stage of the processingbeing currently executed (processing including data reception) in asaving register for bus release 822 and suspends the processing.

In response to the command signal 903, the control part 813 of theelectronic device 1 (802) transmits a response signal 904 for suspendingthe processing and notifying it to the host apparatus 801.

The control part 811 of the host apparatus 801 sends a command signal905 for requesting the host apparatus 801 to transmit data to theelectronic device 2 (803). In response to the command signal 905, thecontrol part 813 of the electronic device 2 (803) transmits a responsesignal 906 (for example, an ACK signal) to the host apparatus 801. Next,data 912 is transmitted from the electronic device 2 (803) to the hostapparatus 801 through the data line 806.

When data transmission between the host apparatus 801 and the electronicdevice 2 (803) is finished, the control part 811 of the host apparatus801 reads out the information that data reception from the electronicdevice 1 has been suspended and the information on the current stage ofthe processing being currently executed (processing including datatransmission) from the saving register 821. Based on the information,the control part 811 finds that the processing has been suspended. Thecontrol part 811 of the host apparatus 801 transmits a command signal(bus return command) 907 for returning to the suspended processing tothe electronic device 1 (802).

The control part 813 of the electronic device 1 (802) receives thecommand signal (bus return command) 907 and transmits a response signal908 including the information that return of processing is possible tothe host apparatus 801 through the command signal line 805.

The control part 811 of the host apparatus 801 reads out the informationon the current stage of the processing being currently executed(processing including data transmission) from a saving register for busrelease 821. Similarly, the control part 813 of the electronic device 1(802) reads out the information on the current stage of the processingbeing currently executed (processing including data transmission) from asaving register 822.

Based on the information on the current stage of the processing beingcurrently executed (processing including data transmission), the controlpart 811 of the host apparatus 801 resumes the suspended datatransmission from the suspended point. In FIG. 9, the control part 811transmits data 913 to the electronic device 1 (802) through the dataline 806.

In the transmission system in accordance with the fifth embodiment ofthe present invention in which plural electronic devices are connectedto one host apparatus through the common data line, even while the hostapparatus is communicating with one electronic device (given that thehost apparatus has no capability to communicate with two targetssimultaneously), the host apparatus can communicate with the otherelectronic device by suspending the communication. After completion ofdata transmission between the host apparatus and the other electronicdevice, it becomes possible to resume data transmission between the hostapparatus and the initial electronic device.

In the transmission system of the present invention, even while oneelectronic device is occupying the data line, data transmission betweenthe other electronic device and the host apparatus can be executed ifnecessary. The host apparatus can resume communicate with the initialelectronic device efficiently (by avoiding waste of transmitting samedata redundantly regardless of being needless). This achieves anadvantageous effect that a transmission system with quick response inwhich plural electronic devices are connected to one host apparatusthrough a common data line, a method for controlling the system, a hostapparatus and electronic devices constituting the transmission systemcan be realized.

In the case where plural functional blocks are mounted in the electronicdevice, input and output terminals of which are regulated according to astandard, such as an IC card, it is difficult to extend the data bus ofthe host apparatus. Accordingly, data transmission between pluralfunctional blocks and the host apparatus need to be executed through acommon data bus. Further, depending on the function, it is required tostart data transmission between plural functional blocks and the hostapparatus rapidly. The present invention achieves an advantageous effectthat a transmission system in which plural functional blocks areoperated through a common data bus and these functional blocks havequick response, a method for controlling the system, a host apparatusand electronic devices constituting the transmission system can berealized.

In the transmission system of the present invention, even while the hostapparatus is communicating with one electronic device, the hostapparatus can suspends the communication if necessary and transmit orreceive data to or from the other electronic device. The host apparatuscan resume communicate with the initial electronic device efficiently.This achieves an advantageous effect that a transmission system withquick response in which electronic devices are connected to one hostapparatus through a common data line, a method for controlling thesystem, a host apparatus and electronic devices constituting thetransmission system can be realized.

Although the invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been changed in the details ofconstruction and the combination and arrangement of parts may beresorted to without departing from the spirit and the scope of theinvention as hereinafter claimed.

INDUSTRIAL AVAILABILITY

The present invention can apply to a host apparatus, electronic devicesand transmission system in which communication between electronicdevices and the host apparatus is executed. For example, the presentinvention can apply to the host apparatus capable of connecting to an ICcard, an IC card and IC card system.

1. A host apparatus comprising: an input/output part having a commandsignal line for transmitting a command signal from the host apparatus toan electronic device and a response signal from said electronic deviceto the host apparatus in response to said command signal, and a dataline, at least a part of which is commonly used by plural electronicdevices and connected to the plural electronic devices, fortransmitting, at least, data in connection with the command signal fromthe host apparatus to said electronic device; and a control part havinga saving register for bus release, wherein data is transmittedconforming to a protocol that the host apparatus serves as a master andsaid electronic devices serve as slaves, the host apparatus transmits acommand signal to said electronic device and then said electronic devicethat received the command signal returns a response signal to the hostapparatus and further, if necessary, data is transmitted from the hostapparatus to the electronic device or from the electronic device to thehost apparatus; and said control part in the state where one of saidelectronic devices is executing the processing that occupies said dataline, when data transmission between the host apparatus and the otherone of said electronic devices is intended to be executed, transmits acommand signal for releasing said data line and suspending saidprocessing to the electronic device that occupies said data line throughsaid command signal line; stores an identifier of the electronic devicethat occupies said data line and the information on the current stage ofsaid processing in said saving register for bus release; aftercompletion of data transmission between the host apparatus and saidother electronic device, reads out the identifier of the electronicdevice that had occupied said data line and the information on thecurrent stage of said processing from said saving register for busrelease; and transmits a command signal for returning to said suspendedprocessing to the electronic device that had occupied said data linethrough said command signal line.
 2. A host apparatus comprising: aninput/output part having a command signal line for transmitting acommand signal from the host apparatus to an electronic device and aresponse signal from said electronic device to the host apparatus inresponse to said command signal, and a data line, at least a part ofwhich is commonly used by plural electronic devices and connected to theplural electronic devices, for transmitting, at least, data inconnection with the command signal from the host apparatus to saidelectronic device; and a control part having a saving register for busrelease, wherein data is transmitted conforming to a protocol that thehost apparatus serves as a master and said electronic devices serve asslaves, the host apparatus transmits a command signal to said electronicdevice and then said electronic device that received the command signalreturns a response signal to the host apparatus and further, ifnecessary, data is transmitted from the host apparatus to the electronicdevice or from the electronic device to the host apparatus; and saidcontrol part in the state where one of said electronic devices isexecuting the processing that occupies said data line, when datatransmission between the host apparatus and the other one of saidelectronic devices is intended to be executed, transmits a commandsignal for releasing said data line and suspending said processing tosaid plural electronic devices connected to said data line through saidcommand signal line; stores information that said data line has beenreleased and information on the current stage of said processing in saidsaving register for bus release; after completion of data transmissionbetween the host apparatus and said other electronic device, reads outthe information that said data line has been released and theinformation on the current stage of said processing from said savingregister for bus release; and transmits a command signal for returningto said suspended processing to said plural electronic devices connectedto said data line through said command signal line.
 3. A host apparatusin accordance with claim 1 or claim 2, wherein said input/output partfurther has an interrupt signal line for transmitting an interruptsignal from said electronic devices to the host apparatus; said controlpart further has an interrupt priority determination part; in the casewhere the host apparatus receives the interrupt signal for requestingdata transmission from the other one of said electronic devices throughsaid interrupt signal line in the state where one of said electronicdevices is executing the processing that occupies said data line; andsaid interrupt priority determination part determines that said datatransmission has a higher priority than the processing that occupiessaid data line, there is a case where data transmission between the hostapparatus and said other electronic device is intended to be executed inthe state where one of said electronic devices is executing theprocessing that occupies said data line.
 4. An electronic devicecomprising: an input/output part having a command signal line fortransmitting a command signal from the host apparatus to an electronicdevice and a response signal from said electronic device to the hostapparatus in response to said command signal, and a data line, at leasta part of which is commonly used by plural electronic devices andconnected to the plural electronic devices, for transmitting, at least,data in connection with the command signal from the host apparatus tosaid electronic device; and a control part having a saving register forbus release, wherein data is transmitted conforming to a protocol thatsaid host apparatus serves as a master and the electronic devices serveas slaves, said host apparatus transmits a command signal to theelectronic device and then the electronic device that received thecommand signal returns a response signal to the host apparatus andfurther, if necessary, data is transmitted from said host apparatus tothe electronic device or from the electronic device to said hostapparatus; and said control part in the state where the electronicdevice is executing the processing that occupies said data line, whenreceiving a command signal for releasing said data line and suspendingsaid processing from said host apparatus, stores information on thecurrent stage of said processing in said saving register for busrelease, suspends said processing and transmits a response signal fornotifying that said processing has been suspended and said data line hasbeen released to said host apparatus through said command signal line;when receiving a command signal for returning to said suspendedprocessing from said host apparatus through said command signal line,transmits a response signal including information that return of saidprocessing is possible and the information as to whether the data lineneeds to be reoccupied or not to said host apparatus through saidcommand signal line, reads out the information on the current stage ofsaid processing from said saving register for bus release, resumes saidprocessing from said stage, and if there is need to reoccupy said dataline, transmits data through said data line.
 5. A method for controllinga transmission system comprising a host apparatus, plural electronicdevices, a command signal line for transmitting a command signal fromthe host apparatus to an electronic device and a response signal fromsaid electronic device to the host apparatus in response to said commandsignal, and a data line, at least a part of which is commonly used byplural electronic devices and connected to the plural electronicdevices, for transmitting, at least, data in connection with the commandsignal from the host apparatus to said electronic device; data istransmitted conforming to a protocol that said host apparatus serves asa master and said electronic devices serve as slaves, said hostapparatus transmits a command signal to said electronic device and thensaid electronic device that received the command signal returns aresponse signal to said host apparatus and further, if necessary, datais transmitted from said host apparatus to the electronic device or fromthe electronic device to said host apparatus, wherein said methodcomprises the steps of: in the state where one of said plural electronicdevices is executing the processing that occupies said data line,transmitting a command signal for releasing said data line andsuspending said processing from the host apparatus to said electronicdevice that occupies said data line through said command signal line inorder to execute data transmission between said host apparatus and theother one of said electronic devices; transmitting a response signal fornotifying that said processing has been suspended and said data line hasbeen released from the electronic device that occupies said data line tosaid host apparatus through said command signal line; after completionof data transmission between said host apparatus and said otherelectronic device, transmitting a command signal for returning to saidsuspended processing from the host apparatus to the electronic devicethat had occupied said data line through said command signal line;transmitting a response signal including the information that return ofsaid processing is possible and information as to whether the data lineneeds to be reoccupied or not from the electronic device that hadoccupied said data line to said host apparatus through said commandsignal line; and if the electronic device that had occupied said dataline need to reoccupy said data line, transmitting data through saiddata line and resuming said processing.
 6. A method for controlling atransmission system comprising a host apparatus, plural electronicdevices, a command signal line for transmitting a command signal fromthe host apparatus to an electronic device and a response signal fromsaid electronic device to the host apparatus in response to said commandsignal, and a data line, at least a part of which is commonly used byplural electronic devices and connected to the plural electronicdevices, for transmitting, at least, data in connection with the commandsignal from the host apparatus to said electronic device; data istransmitted conforming to a protocol that said host apparatus serves asa master and said electronic devices serve as slaves, said hostapparatus transmits a command signal to said electronic device and thensaid electronic device that received the command signal returns aresponse signal to said host apparatus and further, if necessary, datais transmitted from said host apparatus to the electronic device or fromthe electronic device to said host apparatus, wherein said methodcomprises the steps of: in the state where one of said plural electronicdevices is executing the processing that occupies said data line,transmitting a command signal for releasing said data line andsuspending said processing from the host apparatus to said pluralelectronic devices connected to said data line through said commandsignal line in order to execute data transmission between said hostapparatus and the other one of said electronic devices; transmitting aresponse signal for notifying that said processing has been suspendedand said data line has been released from the electronic device thatoccupies said data line to said host apparatus through said commandsignal line; after completion of data transmission between said hostapparatus and said other electronic device, transmitting a commandsignal for returning to said suspended processing from the hostapparatus to said plural electronic devices connected to said data linethrough said command signal line; transmitting a response signalincluding information that return of said processing is possible andinformation as to whether the data line needs to be reoccupied or notfrom the electronic device that had occupied said data line to said hostapparatus through said command signal line; and if the electronic devicethat had occupied said data line need to reoccupy said data line,transmitting data through said data line and resuming said processing.7. A method for controlling a transmission system in accordance withclaim 5 or claim 6, further comprising an interrupt signal line fortransmitting an interrupt signal from said electronic device to the hostapparatus, wherein said method comprises the steps of: in the statewhere one of said electronic devices is executing the processing thatoccupies said data line, said host apparatus receiving an interruptsignal for requesting data transmission from the other one of saidelectronic devices through said interrupt signal line; and determiningthat said data transmission has a higher priority than the processingthat occupies said data line; and based on the result of saiddetermination, there is a case where data transmission between said hostapparatus and said other electronic device is intended to be executed inthe state wherein one of said electronic devices is executing theprocessing that occupies said data line.
 8. A host apparatus comprising:an input/output part having a communication line for transmitting acommand signal from the host apparatus to an electronic device and aresponse signal from said electronic device to the host apparatus inresponse to said command signal; and a control part having a savingregister, wherein data is transmitted conforming to a protocol that thehost apparatus serves as a master and said electronic devices serve asslaves, the host apparatus transmits a command signal to said electronicdevice and then said electronic device that received the command signalreturns a response signal to the host apparatus and further, ifnecessary, data is transmitted from the host apparatus to the electronicdevice or from the electronic device to the host apparatus; and saidcontrol part in the state of performing communication processing withone of said electronic devices, when the host apparatus intends tocommunicate with the other one of said electronic devices, transmits acommand signal for suspending said communication processing to saidelectronic device through said communication line; stores an identifierof said electronic device and information on the current stage of saidcommunication processing in said saving register; after completion ofcommunication between the host apparatus and said other electronicdevice, reads out the identifier of said electronic device and theinformation on the current stage of said communication processing fromsaid saving register; and transmits a command signal for returning tosaid suspended communication processing to said electronic devicethrough said communication line.
 9. A transmission system comprising: ahost apparatus having a register for bus release; plural electronicdevices, each having a register for bus release; a command signal linefor transmitting a command signal from said host apparatus to saidelectronic device and a response signal from said electronic device tosaid host apparatus in response to said command signal; and a data line,via which said plural electronic devices are connected to said hostapparatus and at least a part of which is commonly used by pluralelectronic devices for transmitting, at least, data in connection withthe command signal from the host apparatus to said electronic device,wherein data is transmitted conforming to a protocol that said hostapparatus serves as a master and said electronic devices serve asslaves, said host apparatus transmits a command signal to saidelectronic device and then said electronic device that received thecommand signal returns a response signal to said host apparatus andfurther, if necessary, data is transmitted from said host apparatus tothe electronic device or from the electronic device to said hostapparatus, wherein said host apparatus, in the state where one of saidplural electronic devices is executing the processing that occupies saiddata line, transmits a command signal for releasing said data line andsuspending said processing to said electronic device that occupies saiddata line through said command signal line so that data transmission isexecuted between said host apparatus and the other one of saidelectronic devices, and stores information that said data line has beenreleased and information on the current stage of said processing in saidregister for bus release; said electronic device that has occupied saiddata line transmits a response signal informing that said processing issuspended and said data line is released to said host apparatus throughsaid command signal line, and stores the information that said data lineis released and the information on the current stage of said processingin said register for bus release; after completion of data transmissionbetween said host apparatus and said other electronic device, saidsuspended processing between said host apparatus and the electronicdevice that had occupied said data line is made return, and saidprocessing is resumed from the suspended stage based on the informationread out from said register for bus release respectively.